I am trying to connect the remote ssh server via ruby using
Net::SSH.It is working fine for me for all the commands provided via
script and i could able to read the output of the command
successfully. But when i use the below command it is getting stuck in
SSH.exec!(cmd) and control is not returned from the line. Only if i
click Ctrl+c in command line the script is getting ended. The command
is ./wcsadmin.sh start --> this is used to start the processes of my
application in remote server
Please find the below code snippet of my ruby script:
Net::SSH.start(host, username, :password => password) do |ssh|
puts 'before exit'
output = ssh.exec!(/opt/wcsadmin.sh start)
puts 'Executed command'
The output of the command when i do it manually is :
[root#test bin]# ./wcsadmin.sh start
Starting Network Control System...
This may take a few minutes... stty: standard input: Invalid argument
Network Control System started successfully.
Starting SAM daemon... Done. Starting DA daemon... Starting DA syslog
daemon... start
if i use ssh.exec('./wcsadmin.sh start') the only difference is the
above output is getting printed but still the program is never ended.I
need to manually end it by hitting ctrl+c. When i searched in google i
could find you can use
nohup command('nohup /opt/wcsadmin.sh start >/tmp/teststartserver.log 2>&1')
to skip the hangup signals and tried the same.This also writes the output to teststartserver.log but
getting hanged.Can anyone please help me out on this issue?
Thanks in Advance!
Thanks, Meena
If the command itself doesn't return right away, then SSH.exec! will block further execution until the command returns. If for some reason you lose remote contact, then SSH.exec! may not know that you have lost connectivity and it will continue to block.
You could try putting the command in the background:
output = ssh.exec!('/opt/wcsadmin.sh start &')
Or maybe look at the documentation on that command and maybe it has some sort of --no-wait option that will allow it to return immediately, even if it is still working.
Related
I'm looking for some help with a script of mine. I'm new at bash scripting and I'm trying to start a service on a remote host with ssh and then capture all the output of this service to a file in my local host. The problem is that I also want to execute other commands after this one:
ssh $remotehost "./server $port" > logFile &
ssh $remotehost "nc -q 2 localhost $port < $payload"
Now, the first command starts an HTTP server that simply prints out any request that it receives, while the second command sends a request to such server.
Normally, if I were to execute the two commands on two separate shells I would get the first response on the terminal, but now I need it on the file.
I would like to have the server output all the requests on the log file, keeping a sort of open ssh connection to receive any new output of the server process.
I hope I made myself clear.
thank you for your help!
EDIT: Here's the output of the first command:
(Output is empty in the terminal... it waits for requests).
As you can see the commands doesn't return anything yet but it waits.
When I execute the second command on a new terminal (the request), the output of the first terminal is the following:
The request is displayed.
Now I would like to execute both commands in sequence in a bash script, sending the output of the first terminal (which is null until the second command is run) to a file so that ANY output, triggered by later issued requests, is sent to a file.
EDIT2: As of now, with the commands above, the server answers any requests but the output is not registered in the log file.
I am connecting to a remote host via ssh login and running logstash by the following command
$./logstash -f first-pipeline.conf
However, after I logout from the server, the logstash stops running. How to enable it to keep running even after I logout. Thanks.
Another approach is to use the screen command which can be very useful for this.
First you open your SSH session, then type screen at the prompt. That opens a new session in which you can run your logstash command.
When it runs, you simply press Ctrl+a d in order to detach your self from that screen and you can safely logout.
Whenever you log back into your SSH session, you enter screen -r and you will get back into your previous session where logstash was started.
You can create as many "screens" as you wish to start many different processes at different times.
Also see this comparison between using nohup and screen
Just run it as an agent
$ logstash agent -f ~/logstash/pipeline.conf
I have the current scenario to deal with:
I have to schedule the backup of my company's Linux-based server (under Suse Linux) with ARCServe R15 (installed on Windows 2003R2SP2).
I know I have the ability in my backup software (ARCServe) to add pre/post execution scripts to my backup-jobs.
If failure of the script, ARCServe would be specified NOT to run the backup-job, and if success, specified to be run. I have no problem with this.
The problem is, I want to make a windows script (to be launched by ARCServe) for executing a Linux script on the cluster:
- If this Linux-script fails, I want my windows-script to fail, so my backup job in ARCServe wouldn't run
- If the Linux-script success, I want my windows-script to end normally with error code 0, so my ARCServe job would run normally.
I've tried creating this batch file (let's call it HPC.bat):
echo ON
start /wait "C:\Program Files\PUTTY\plink.exe" -v -l root -i "C:\IST\admin\scripts\HPC\pri.ppk" [cluster_name] /appli/admin/backup_admin
exit %errorlevel%
If I manually launch this .bat by double-clicking on it, or launching it in a command prompt under Windows, it executes normally and then ends.
If I make it being launched by ARCServe, the script seems never to end.
My job stays in "waiting" status, it seems the execution code of the linux script isn't returned to my batch file, and this one doesn't close.
In my mind, what's happening is plink just opens the connection to the Linux, send the sript execution signal, and then close the connection, so the execution code can't be returned to the batch. Am I right ?
Is what I want to do possible or am I trying something impossible to do ?
So, do I have to proceed differently ?
Do I have to use PUTTY or CygWin instead of plink ?
Please, it's giving me headaches ...
If you install Cygwin, you could do it exactly like you can do it on Linux to Linux, i.e. remotely run a command with ssh someuser#remoteserver.com somecommand
This command will return with the same return code on the calling client, as the command exited with on the remote end. If you use SSH shared keys for authentication instead of passwords, it can also be scripted without user interaction.
I'm running a Bukkit (Minecraft) server on a Linux machine and I want to have the server gracefully shut down using the server's stop command and the computer suspend at a certain time using pm-suspend from the command line. Here's what I've got:
me#comp~/dir$ perl -e 'sleep [time]; print "stop\\n";' | ./server && sudo pm-suspend
(I've edited by /etc/sudoers so I don't have to enter my password when I suspend.)
The thing is, while the perl -e is sleeping, the server is expecting a constant stream of bytes, (That's my guess. I could be misunderstanding something.) so it prints out all of the nothings it receives, taking up precious resources:
me#comp~/dir$ ...
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>...
Is there any such thing as a buffered pipe? If not, are there any ways to send delayed input to a script?
You may want to have a look at Bukkit's wiki, which recommends an init script for permanently running servers.
This init script uses rather unconventional approach to communicate with running server. The server is started in screen session, then all commands are send to the server console via screen, e.g.
screen -p 0 -S $SCREEN -X eval 'stuff \"stop\"\015'
See https://github.com/Ahtenus/minecraft-init/blob/master/minecraft
This approach suggest that bukkit may be expecting standard input to be attached to a terminal, thus requiring screen wrapper (which is itself terminal emulator) for unattended runs.
I have a master-workers architecture where the number of workers is growing on a weekly basis. I can no longer be expected to ssh or remote console into each machine to kill the worker, do a source control sync, and restart. I would like to be able to have the master place a message out on the network that tells each machine to sync and restart.
That's where I hit a roadblock. If I were using any sane platform, I could just do:
exec('ruby', __FILE__)
...and be done. However, I did the following test:
p Process.pid
sleep 1
exec('ruby', __FILE__)
...and on Windows, I get one ruby instance for each call to exec. None of them die until I hit ^C on the window in question. On every platform I tried this on, it is executing the new version of the file each time, which I have verified this by making simple edits to the test script while the test marched along.
The reason I'm printing the pid is to double-check the behavior I'm seeing. On windows, I am getting a different pid with each execution - which I would expect, considering that I am seeing a new process in the task manager for each run. The mac is behaving correctly: the pid is the same for every system call and I have verified with dtrace that each run is trigging a call to the execve syscall.
So, in short, is there a way to get a windows ruby script to restart its execution so it will be running any code - including itself - that has changed during its execution? Please note that this is not a rails application, though it does use activerecord.
After trying a number of solutions (including the one submitted by Byron Whitlock, which ultimately put me onto the path to a satisfactory end) I settled upon:
IO.popen("start cmd /C ruby.exe #{$0} #{ARGV.join(' ')}")
sleep 5
I found that if I didn't sleep at all after the popen, and just exited, the spawn would frequently (>50% of the time) fail. This is not cross-platform obviously, so in order to have the same behavior on the mac:
IO.popen("xterm -e \"ruby blah blah blah\"&")
The classic way to restart a program is to write another one that does it for you. so you spawn a process to restart.exe <args>, then die or exit; restart.exe waits until the calling script is no longer running, then starts the script again.